The present invention relates to an apparatus for cooling dust or finely granular bulk material, having a vertical cylindrical cooling jacket, the externally cooled cylindrical surface of which is fed with the material to be cooled from the inside by means of an annular conveyor worm which conducts the material upward and presses it by the centrifugal force against the heat exchange surface, the conveyor worm which is turnable about a central axis being driven by a motor.
Cooling devices of the type described above are known, in particular for the cooling of cement and cement grit. The material to be cooled is fed to the cylindrical container from below through an inlet connection, taken up by the worm threads which are rotating at high speed, thrown slung against the wall of the container and, at the same time, conveyed upward towards the outlet opening. During this conveying process, cooling water flows down on the outer wall of the container which is preferably divided into sectors, and cools the wall and thus indirectly the material, the material giving off its heat by contact with the container wall. The heated cooling water flows back into a cooling system where it is again cooled down to the required temperature.
The advantages of such a cooling device consist in the fact that within only a relatively small space an effective cooling of the fine material is obtained. The formation of a crust by condensation is substantially prevented by the rotating conveyor worm. The cooling device is therefore also suitable for the cooling of slaked lime, coal fines and fertilizers.
Since dust and finely granular bulk material are subject to explosion at a certain concentration of dust in case a spark or incandescent pockets are formed, the known cooling device cannot be used, for instance, for coal dust or other explosive substances.